How do I attach a hot end to Wades extruder?

I was just putting my hot end onto my new Wades extruder when I realised I can't see how

I can see that there are some holes that can take M3(+) screws (leading to the large hole that will take the 16mm PTFE barrier).

The wiki page (http://reprap.org/wiki/Wade%27s_Geared_Extruder#The_Hot_End_...) says "Attach a length of 16 mm OD PTFE using the two M bolts to pin it in place. I pre-drilled the PTFE mounting holes with a 2.3 mm drill, which made for a tight friction fit." but I'm not 100% certain what "M bolts" it means. Also the holes I mean are more like tight M4 holes (not 2.3 mm)

Near the top of that wiki page it gives lists these parts for mounting the hot end

2 X M3X35 bolts;
4 X M3 washers;
2 X M3 nuts;

Do I need to melt 2 M3 nuts into the extruder where the 16mm PTFE barrier goes in?

Thanks

Pete

You should insert the insulator in the bracket and drill through with a 2.5mm drill and then screw through the M3 bolts. The idea being they tap an M3 thread in the soft plastic. That might be hard work. I use an M3 tap. I have also used M2.5 bolts. Drilling through a bit bigger would also make it easier.

You don't need any nuts as they wont go anywhere with the downwards force.

Edited 1 time(s). Last edit at 05/25/2011 01:30PM by nophead.

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[www.hydraraptor.blogspot.com]

Of course - obvious now I see what you say

I think that I assumed I couldn't touch the PTFE barrier at all but of course there 6.5mm plastic each side of the 3mm central hole to play with.

I expect I'll drill a 3mm hole and go with that

Cheers

Pete

If you use a 3mm drill to drill out the PTFE, you won't get as tight a fit, and your hot end may wobble during printing. Why not use the 2.3 or 2.5 mm bit as suggested?

Wade

I use four M4x8mm set screws through the four holes on the sides, right on to PTFE insulator. I don't drill into the insulator, just clamp it using the set screws. It fits really tight, and does not wobble when printing (Wildseyed hot end)

OK,

Will start with 2.5 mm
Stupid question: If I use a 2.5mm drill doesn't that mean it'll be too tight to even get the 3mm screws in at all? That's why I assumed I should start with a 3mm drill. I guess not

I like the idea of the M4 set screws too but am a tad worried about ruining the holes if I get it wrong

Cheers

Pete

2.5mm is the correct size for tapping M3. I.e. the inner diameter of the thread is about 2.5mm. If you have an M3 tap it is perfect. Without a tap it might be hard work to tap the thread with the screw, but possible, especially with ABS rather than PLA.

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[www.hydraraptor.blogspot.com]

I use M4 because that's what the local Home Depot carries. I probably would not go smaller, simply because I am supporting the entire extruder with these on the PTFE, which is not a hard material. I'm actually quite surprised that it works. But it does beautifully.